The research was to investigate the best conditions for liquid fermentation of Bacillus amyloliquefacien 15-1-1 strain and increase the antagonistic substance productivity of strain 15-1-1. The single factor experi-ments and orthogonal experiments were adopted to optimize the liquid fermentation medium and conditions. The re-sults showed that optimum medium formula was glucose 2.0%, peptone 0.5%, yeast extract 1.0%, Na Cl 0.5%. Theoptimal fermentation conditionals were as follows: initial p H value of medium 7.0, fermentation temperature 32℃,5% inoculation volume, 40 mL ventilation, cultured in 250 mL flask for 36 h.